Connection Quality Analytics (CQA)

When a client sends a TCP request, CQA monitors and extracts a large amount of detailed TCP layer data during an active connection. With the extracted data, CQA uses a heuristic learning algorithm to derive important characteristics of the connection, for example, network type (2G, 3G or 4G), congestion level (None, Low, Medium, or High), and signal quality (Excellent, Good, Fair or Poor) on a per-subscriber basis. Citrix ADC then stores the information in a subscriber store (so that it can be available for the next TCP connections from the same subscriber) and exports the data to the AppFlow collectors. The stored information is as raw values in a composite format that defines the network type, congestion level, and signal quality of the subscriber connection. The detected characteristics can be used for other applications, for example, to intelligently apply different TCP profiles for different network characteristics. For more information, see topic Adaptive TCP.

Benefit

Enable mobile operators to:

Understand congestion level of a subscriber network.

Analyzing overall network behavior of a subscriber.

Prerequisites

The CQA feature works on Telco platforms with the purchase of a basic CBM license and CBM Premium license and for otherCitrix ADC platforms, the feature works with the purchase of a CNS Platinum license. Before you configure the TCP optimization feature, your appliance must have a suitable license installed.

Configuring Connection Quality Analytics (CQA)

To optimize a TCP traffic using CQA technique, begin by enabling CQA and Appflow features on the appliance. When the appliance receives a client TCP connection request, it monitors the incoming traffic and uses the CQA configuration to derive CQA parameters from the raw TCP metrics.

Configure CQA by using the CLI

To configure CQA on a Citrix ADC appliance, you can perform the following tasks:

Enable CQA

Enable AppFlow Collector

Configure CQA Parameters

Verify CQA feature

Using CQA-based PI expressions

Enabling CQA

If you want the Citrix ADC appliance to extract TCP raw metric and derive CQA parameters, you must enable the CQA feature and set adaptive TCP to ON. You must also enable the Appflow feature so that the appliance can send the derived CQA data for network analysis.

To enable CQA:

At the command prompt, type the following command:

enable ns feature cqa

To enable Appflow collector:

You must have at least one Appflow collector to be running in your appliance. At the command prompt, type the following command:

enable ns feature appflow

Configuring CQA Parameters

For CQA to derive parameters such as network type, signal quality, and congestion level, you must configure CQA settings on the appliance.

Below are sample PI expressions with CQA parameters such as network type, congestion level, and signal quality, evaluates an incoming traffic of network type 2G, exhibiting good or excellent signal quality with a high congestion level:

Adaptive TCP Optimization

As subscribers in a telco network increase in an unprecedented rate, it is important to provide a quality user experience to each subscriber. To achieve this, Citrix ADC uses an advanced optimization technique called Adaptive TCP. The technique optimizes traffic by independently adapting different TCP profiles for each subscriber based on the information stored in a subscriber (UX) store. The UX store contains subscriber’s details (such as network type, signal quality, and congestion level) in a composite format. When a client sends a TCP request, the appliance queries the store for the subscriber information and applies a suitable TCP optimization based on subscriber’s network conditions. The appliance does this by enabling Adaptive TCP feature on a Citrix ADC TCP profile.

Benefit

Using Adaptive TCP optimization technique, a mobile operator can:

Extract advanced and detailed insight of network conditions experienced by a mobile subscriber.

Automatically adapt traffic management actions of Citrix ADC based on the current network conditions.

Prerequisites

The Adaptive TCP feature works only on telco traffic management platforms (such as Citrix ADC T1000 series and VPX-T platforms) with a Premium license. The VPX-T software and T1000 hardware appliances are designed to meet the needs of telco mobile operators and service providers. Before you configure the TCP optimization feature, your appliance must have the following license files installed:

Configuring Adaptive TCP

The configuration begins by enabling CQA, Appflow, and Adaptive TCP features. Once you enable, you can configure a normal TCP profile with ‘applyAdaptiveTcp’ option enabled and scrutinizing TCP parameters such as TCP favor, TCP Max congestion window, Burst Rate Control (pacing), TCP Rate, and TCP Rate Maximum Queue. When the appliance receives a TCP request, it applies a TCP profile and Adaptive TCP logic is triggered. The logic queries the subscriber store for the subscriber’s CQA information. Based on the derived metrics, the appliance independently adapts the TPC profile to optimize the subscriber traffic.

Configuring Adaptive TCP by using the CLI

To configure Adaptive TCP, you must perform the following tasks:

Enable CQA, AppFlow, and Adaptive TCP features

Add load balancing virtual server for TCP traffic

Add load balancing virtual server for HTTP traffic

Set TCP profile parameters

Apply TCP Profile either by:

Associating the TCP profile to load balancing virtual server.

Using policy-based TCP optimization.

Adding an AppQoE action

Adding an AppQoE policy

Binding AppQoE policy to a TCP loading balancing virtual server

Enabling Adaptive TCP

If you want the appliance to optimize TCP traffic, you must enable CQA, AppFlow, and Adaptive TCP features.

To add AppQoE action for policy-based Adaptive TCP optimization

In the Create AppQoE Action screen, type or select values for the parameters. The contents of the dialog box correspond to the parameters described in “Parameters for configuring the AppQoE Action” as follows (asterisk indicates a required parameter):

Name—name

Action type—PRIORITY_QUEUING

TCP Profile—Apply a TCP profile by adding a new one or selecting an existing one.

Priority—HIGH

Policy Queue Depth—0

Queue Depth—0

Click Create and OK.

To add AppQoE policy for policy-based Adaptive TCP optimization

In the Create AppQoE Policy screen, type or select values for the parameters. The contents of the dialog box correspond to the parameters described in “Parameters for configuring the AppQoE Policy” as follows (asterisk indicates a required parameter):

Name—name

Action—Associate an action to perform when the policy rule matches the TCP connection. You can associate by adding a new action or selecting an existing one.

Expression—In the Rule text box, either enter the policy expression with CQA parameters or use the expression editor to create a rule.

In the details pane, select a load balancing virtual server of type HTTP or TCP and click Edit.

In the Load Balancing Virtual Server page, go to Policies section and click the + icon.

In the Policies slider page, do the following:

Choose policy. Policy name.

Choose type. Policy type as request or response.

Click Continue to close the slider page and go to the main page.

Click Done.

Analytics and Reporting

The TCP Speed Reporting is a Citrix ADC feature which extracts a rich set of TCP-level statistics, as a measure of TCP download and upload performance, and is utilized in TCP Insight reports of the Citrix Application Delivery Management (ADM) . To achieve this, Citrix ADC monitors each TCP connection, locates packet bursts on an idle time-out basis and reports key metrics (such as byte count, retransmitted byte count, an duration) for the identified maximum burst. In addition to this, the TCP raw metrics such as RTT, BIF, receive window and so forth are also measured based on the optimization type (endpoint or transparent) that you configure. The TCP Speed Reporting feature is enabled by default, supports both TCP and HTTP vServers and depends on Appflow/ULFD reporting infrastructure. For more information, see Analytics and Reporting.

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